What could be the cause for spasm or pulsating sensation in entire rib cage?

hello. i have an annoying twitch/spasm/pulsating sensation in my entire rib cage. This is about halfway down from my armpit (sideview, not in the front or back, just side), and more on the left side than the right. there is no pain, and contractions/spasm would last about 2 seconds or so, it occurs every 6-8 minutes on average, occurring for the past 24 hours. It feels more like someone is tightening their grip around that area and then releasing.

Brief Answer:
Inadequate hydration state & electrolyte imbalance
Detailed Answer:
Hello,
Thanks for your query.
Regarding the symptoms as mentioned in your post, kindly let us know about the following:
1. Involuntary twitching of muscles can be due to neurological damage secondary to Hypertension & Diabetes (known as Hypertensive neuropathy & Diabetic neuropathy respectively).
Is there is significant past history of systemic disease like Diabetes, Hypertension, Thyroid disorder, etc. ?
2. Any recent history of Stress, improper nutrition & lack of sleep?
3. Habit of alcohol consumption?
4. History of prolonged intake of certain medications?
5. Any other associated features like inability to concentrate or remember things, dizziness, visual disturbances, nausea, etc.?
If your answer to the above mentioned questions is NO, then the symptoms can be attributed to inadequate hydration status & electrolyte imbalance of the body or dietary deficiencies of certain nutrients like Iron, Calcium, Vitamin D, Vitamin B 12, Folic acid, etc. which help in blood formation & nerve conduction.
Symptomatic relief can be obtained by intake of nervigenic agents as well as multivitamin & multimineral supplements including iron, calcium & Vit D needs to be added in your diet.
If you still find any difficulty, kindly get certain investigations like fresh estimation of blood pressure & blood sugar levels, Thyroid profile & nerve conduction studies to rule out any pathological cause for the symptoms.
There is no need to worry, you will be fine.
Till then, maintain adequate hydration & proper nutrition status, exercise regularly and avoid stress.
Wishing you a Good Health.
Please let me know if I need to clarify further.
Take care.